Molecular and genetic analysis of CDK-5 function in synaptic transmission

描述(申请人提供)：谷氨酸是大脑中主要的兴奋性神经递质。突触上AMPA型谷氨酸受体(GluRs)丰度的活性依赖变化可以改变突触强度，是参与学习和记忆的主要细胞机制。GluRs的异常调节导致了缺血、中风和一些神经退行性疾病中兴奋性毒性细胞的死亡。因此，了解参与调节突触GluR定位和丰度的细胞生物学和分子机制是非常重要的。这项研究的长期目标是定义调节突触处GluRs丰度的基因和机制。我们对突触AMPAR插入(胞吞作用)和移除(胞吞作用)的机制的了解已经取得了很大的进展。然而，对调节GluR从细胞体顺行运输到突触的马达和适配器的了解要少得多。这项建议的重点是了解参与调节运动依赖的GluR从细胞体到突触的运输的基本机制。我们使用线虫作为遗传模型来研究体内调节GluR运输的基因和机制。我们最近发现，蛋白激酶CDK-5促进线虫Glur-1的顺行运输，而KLP-4/KIF13是这一作用所必需的。在初步研究中，我们发现两个microRNAs(miR-75和miR-79)和AP2网状蛋白适配蛋白亚基APM-2/？2是GLR-1顺行转运的新调节因子。我们还发现，GLR-1的稳定性可能与KLP-4依赖的顺行转运有关。在这项提案中，目标1将研究APM-2/？2在GluRs顺行贩运中的新功能。目的2将研究激酶CDK-5和microRNAs调节依赖于KLP-4的运输的机制。目的3将研究依赖KLP-4的顺行转运与GLR-1降解的耦合机制。识别调节突触GluR水平的基因和机制可能为减少GluR介导的中风和缺血后的兴奋性毒性提供潜在的治疗靶点。

DESCRIPTION (provided by applicant): Glutamate is the major excitatory neurotransmitter in the brain. Activity-dependent changes in the abundance of AMPA-type glutamate receptors (GluRs) at synapses can alter synaptic strength and are a major cellular mechanism involved in learning and memory. Aberrant regulation of GluRs contributes to excitotoxic cell death in ischemia, stroke and several neurodegenerative disorders. Thus it is important to understand the cell biological and molecular mechanisms involved in regulating GluR localization and abundance at synapses. The long-term goal of this research is to define genes and mechanisms that regulate the abundance of GluRs at synapses. Great progress has been made in our understanding of the mechanisms involved in AMPAR insertion (exocytosis) and removal (endocytosis) at synapses. However, much less is known about the motors and adaptors that regulate anterograde trafficking of GluRs from the cell body to the synapse. The focus of this proposal is to understand the fundamental mechanisms involved in regulating motor-dependent transport of GluRs from cell bodies to synapses. We use C. elegans as a genetic model to study genes and mechanisms that regulate the trafficking of GluRs in vivo. We recently showed that the protein kinase CDK-5 promotes anterograde trafficking of GLR-1, a C. elegans GluR, and that the kinesin 3 motor KLP-4/KIF13 is required for this effect. In preliminary studies, we identify two microRNAs (miR-75 and miR-79), and the AP2 clathrin adaptin subunit APM-2/¿2, as novel regulators of GLR-1 anterograde transport. We also discovered that GLR-1 stability may be coupled to KLP-4-dependent anterograde transport. In this proposal, Aim 1 will investigate a novel function for APM-2/¿2 in the anterograde trafficking of GluRs. Aim 2 will investigate mechanisms by which the kinase CDK-5 and microRNAs regulate KLP-4-dependent trafficking. Aim 3 will investigate mechanisms that couple KLP-4-dependent anterograde transport to GLR- 1 degradation. Identifying genes and mechanisms that regulate GluR levels at synapses may provide potential therapeutic targets for reducing GluR-mediated excitotoxicity after stroke and ischemia.